Mobile electronic devices, such as digital cameras, personal digital assistants (PDA's), and cell phones continue to increase in popularity. Such portable devices are commonly manufactured using application specific integrated circuit (ASIC) designs. Conventional ASIC design involves development of medium complexity integrated circuits (ICs) essentially comprising core logic and some hard macros, such as on-chip static random access memories (SRAMs). However, as semiconductor processing technology continues to advance, more complicated IC designs have evolved, such as system-on-chip (SoC) designs.
A continuing trend is to manufacture mobile electronic devices utilizing SoC designs. However, while often referred to as SoC devices, conventional SoC-based mobile electronic devices continue to utilize memory devices that are not part of the SoC. These “off-chip” memory devices can be broadly categorized as either removable or non-removable devices.
Non-removable memory devices typically comprise volatile memory devices, such as SRAM or dynamic random access memory (DRAM) devices, which are located on a printed circuit board (PCB) along with the associated SoC. Such memory have a high degree of reliability, with each bit basically being guaranteed as “good” by manufacturers, which has led to these devices sometimes being referred to as “perfect” memory devices. These so-called perfect memory devices do not require error correction means, and thus greatly simplify the design and reduce the cost of any memory control/interface circuitry internal to the SoC. However, the memory devices themselves can be expensive and can potentially consume large amounts of limited battery capacity.
Removable memory devices are generally some type non-volatile flash memory device used for data storage and typically comprise some type of removable form factor card, such as a CompactFlash (CF) or Smart Media card. Memory cards provide flexibility as to the memory requirements of an individual user and remove the cost of the memory device from the initial cost of the mobile electronic device, thus making them more attractive to consumers. However, while the cost of the memory device itself is eliminated, removable memory devices require costly interface circuitry. In addition to expensive physical interface connections between the device and the memory card, such as the male/female pin configuration of a CF card, some SoC-based mobile electronic devices continue to utilize a separate memory controller chip to support the addressing/error correction required to support communication between the SoC and the memory card. Additionally, the memory controller and physical interface are essentially duplicated as part of the removable memory card, further raising the ultimate cost of the device to a consumer. Also, while continually being increased, the storage capacities of these devices is still relatively limited as driven by cost and/or space concerns.